Method of painting polyolefin substrate

ABSTRACT

AN IMPROVED METHOD OF COATING A SOLID SUBSTRATE OF POLYOLEFIN WITH AN ADHERENT COATING OF A COPOLYMER OF ACRYLIC MONOMERS CROSSLINKED WITH VINYL MONOMERS WHICH COMPRISING APPLYING TO THE POLYOLEFIN SUBSTRATE A FILM-FORMING SOLUTION WHICH, ON A PIGMENT AND PARTICULAR FILLERFREE BASIS CONSISTS ESSENTIALLY OF 8A) ABOUT 15 TO ABOUT 45 WEIGHT PERCENT ACRYLATE SELECTED FROM THE GROUP CONSISTING OF DIACRYLATES AND DIMETHACRYLATES OF A C2-C12 A ALKANE DIOL, DIACRYLATES AND DMETHACRYLATES OF A C4-C12 POLYETHER DIOL, AND TRIACRYLATES AND TRIMETHACRYLATES OF A C6-C12 TRIOL, AND (B) 55 TO 85 WEIGHT PERCENT OF A VINYL RESINCOMPRISING COMPONENT CONSISTING OF 0 TO ABOUT 85 WEIGHT PERCENT MONOVINYL MONOMERS AND ABOUT 15 TO 100 WEIGHT PERCENT OF AN ALPHA-BETA OLEFINICALLY UNSATURATED COPOLYMER OF ACRYLIC MONOMERS CONTAINING BETWEEN ABOUT 0.5 AND ABOUT 5 UNITS OF ALPHA-BETA OLEFINIC UNSATURATION PER 1,000 UNITS MOLECULAR WEIGHT AND CROSSLINKING THE LIQUID COATING ON THE POLYOLEFIN SUBSTRATE BY EXPOSING THE COATING TO A BEAM OF POLYMERIZATION EFFECTING ELECTRONS HAVING AVERAGE ENERGY IN THE RANGE OF ABOUT 100,000 TO ABOUT 500,000 ELECTRON VOLTS.

May 7, 1974 E J, ARONOFF ETAL 3,809,569

y' METHOD 0F PAINTING 'POLYOLEFIN sUBsTRATE Original .Filed Aug. 4, 1969 CUPON/145@ ATTORNEYS United States Patent O Int. Cl. B44d 1/50; C081? 3/ 64 U.S. Cl. 117-9331 6 Claims ABSTRACT OF THE DISCLOSURE An improved method for coating a solid substrate of polyolefin with an adherent coating of a copolymer of acrylic monomers crosslinked wtih vinyl monomers which comprises applying to the polyolefin substrate a film-forming solution which, on a pigment and particulate iillerfree basis consists essentially of (A) about 15 to about 45 weight percent acrylate selected from the group consisting of diacrylates and dimethacrylates of a Cz-Cm alkane diol, diacrylates and dimethacrylates of a C4-C12 polyether diol, and triacrylates and trimethacrylates of a CG-Clg triol, and (B) 55 to 85 weight percent of a vinyl resincomprising component consisting of to about 85 weight percent monovinyl monomers and about 15 to 100 weight percent of an alpha-beta oletinically unsaturated copolymer of acrylic monomers containing between about 0.5 and about 5 units of alpha-beta olenic unsaturation per 1,000 units molecular weight and crosslinking the liquid coating on the polyolen substrate by exposing the coating to a beam of polymerization effecting electrons having average energy in the range of about 100,000 to about 500,000 electron volts.

This application is a continuation of Ser. No. 847,230, iiled Aug. 4, 1969, and now abandoned.

This invention relates to polyolefin substrates bearing a tenaciously adhering vinyl paint film. The term polyolefin as used herein refers to polyethylene, polypropylene and ethylene-propylene copolymers.

Previous attempts to effectively paint polyolefn substrates with a vinyl resin comprising paint without pretreatment of the polyolefin substrates have been characterized by extremely poor adhesion between paint film and substrate. Even vinyl resin-vinyl monomer paints which have exhibited excellent adhesion when polymerized on other substrates with ionizing radiation fail to adhere effectively to a polyoleiin substrate.

Surprisingly, it has been found that the adhesion of a vinyl resin or vinyl resin-monovinyl monomer paint binder to a polyolefin substrate is unexpectedly and dramatically improved if the paint binder contains at least about l5 weight percent of certain acrylates, hereinafter defined, and the lm is polymerized upon the polyolefin surface with a beam of electrons having average energy in the range of about 100,000 to about 500,000, preferably about 150,000 to about 450,000 electron volts.

The term acrylate as used herein includes esters 0f an alcohol and either acrylic acid or methacrylic acid, i.e. acrylates and methacrylates.

n ICC The critical elements in this invention are the use of sufiicient quantities of the selected acrylates, their use with a vinyl unsaturated paint binder resin and the crosslinking of the same with the electron beam on the surface of the polyolein.

The drawing shows an electron polymerized dior triacrylate-vinyl resin paint on the surface of acrylonitrilebutadiene-styrene copolymer.

The acrylates used in this invention may be divided into three groups. In the lirst embodiment, the acrylate is a diacrylate, dimethacrylate, or monoacrylate-monomethacrylate of a Cz-Cm alkane diol, i.e. the diester of one molar amount of a C2-C12 alkane diol and two molar amounts of acrylic acid or methacrylic acid or one molar amount of each. Such diols include ethane diol (ethylene glycol) propane diol, butane diol, hexane diol, octane diol, decane diol, and dodecane diol. These diols may be either straight or branched chain diols. In the second embodiment, the acrylate is a diacrylate, dimethacrylate or monoacrylate-monomethacrylate of a C4-C12 polyether diol. Such diols include diethylene diols (glycol), dipropylene diol, triethylene diol, tetraethylene diol, and tetrapropylene diol. In the third embodiment, the acrylate is a triacrylate, trimethacrylate, monoacrylate-dimethacrylate, diacrylate-monomethacrylate of a Cs-Cm triol, e.g. trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4,10 decane triol triacrylate, 1,4,l0-decane triol trimethacrylate, 1,5,12-dodecane triol triacrylate, 1,5,12- dodecane triol trimethacrylate, etc. On a pigment, mineral iiller and'nonpolymerizable solvent-free basis, the paint binder solution contains about 15 to about 45, preferably about 20 to about 35, Weight percent of one of the aforementioned acrylates or mixtures thereof.

The balance of the paint binder solution, i.e. 55 to 85 weight percent of the total, is made up of a vinyl unsaturated paint binder resin and optionally monovinyl monomers. The vinyl resin used in this paint is a vinyl monomer-comprising copolymer and comprises about 15 to about 100 weight percent of the balance. 'Ihe monovinyl monomers comprise 0 to 85, advantageously 5 to 85, and preferably to 85, weight percent of the balance. Advantageously such resins have average molecular weights in the range of about 1,000 to about 25,000, preferably 5,000 to 15,000.

The vinyl *resin used has above about 0.5 and below about 5 units of alpha-beta olelinic unsaturation per 1,000 units molecular weight, preferably about 0.7 to

about 3 of such units per 1,000 units molecular weight.

A preferred vinyl resin is prepared by copolymerizing acrylates such as methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethy1 hexyl acrylate, etc. and an amount of glycidyl methacrylate commensurate with the amount of unsaturation desired. This is introduced in a second step reaction by reacting this copolymer with acrylic or methacrylic acid. Other vinyl resins are illustrated in the examples that follow.

The monovinyl monomer component when used may be styrene, methyl methacrylate, ethyl acrylate, hydroxyethyl methacrylate, butyl acrylate, butyl methacrylate, Z-ethylhexyl methacrylate, mixtures of the same, etc.

In this specification the term pain is meant to include pigment and/ or particulate filler, the binder without pigment and/or ller or having very little of the same, Y

EXAMPLE 1 An alpha-beta oletmically unsaturated vinyl resin, resin A, is prepared in the following manner.

Starting materials: Parts by weight Xylene 600 Methyl methacrylate 196 Ethyl acrylate 333 Glycidyl methacrylate n 7l Azobisiso butyronitrile 6 Hydroquinone 0.12 Methacrylic acid '42 Triethyl amine 0.96

Procedure The solvent, xylene, is charged to a iiask tted with a stirring rod, an addition funnel, a thermometer, a nitrogen inlet tube and a condenser. The amount of xylene'is 'l equal to the total weight of vinyl monomersto be added. The xylene is heated to reflux, nitrogen is bubbled through the solution during heat up and throughout the reaction. The combined monomers, excepting the methacrylic acid, and initiator (azobisiso butyronitrile) are added to the reuxing solution evenly over a two-hour period. The initiator weight is 10 parts by weight per 1,000 parts by weight vinyl monomers. The reaction solution is re` fluxed until the conversion of monomer to polymer is greater than about 97 percent.

In the second step, hydroquinone is added as an inhibi-l tor and then the methacrylic acid is added to' react with the epoxy groups on the polymer. Triethyl amines used as a catalyst. This esterication reaction is carried v'out at reflux temperatures until about 80 percent esterication is accomplished (determined by residual acid number); The xylene is then removed by vacuum distillation and the polymer is recovered. t

Control test #l A paint binder solution is formed from' 25 parts by weight resin A and 75 parts by weight methyl methacrylate. Thissolution is applied to the surface of differ-v TABLE I Adhesion test- Paint formulation I (resin A 25%? methyl methacrylate 75%) Substrate: Adhesion, percent Polypropylene 0 Propylene-ethylene copolymer 0 High density polyethylene `0 Control test #2 i i I A second test is prepared using the same procedure except that in the paint binder solution the resin component is increased to 50 parts by weight and that of the monovinyl monomer reduced to 50 parts by 'Weight` The,

adhesion test is carried out upon the cured coatings as before, and the results are Set fQrh blOWv TABLE` I I Adhesion test-Paint formulation II (resin A 50%- methyl methacrylate 50%) Substrate: Adhesion, percent Polypropylene 0 Propylene-ethylene copolymer 0 High density polyethylene 0 Control test #3 A third test is prepared using the same procedure except that in the paint binder solution the vinyl monomer component is changed to butyl 'acrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests andthe results are set forth below;

TABLE III Adhesion tem-Paint formulation Infr'esin A 50%-birty1 acrylate 50%) Substrate: Adhesionjperc'e'nt Polypropylene 0 Propylene ethylene copolymer 0 High density polypropylene ;g 0

Control test #4 A fourth test is -prepared using the same procedure except that in the paint binder solution the vinyl monomer component is changed to Z-ethylhexyl acrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE IV Adhesion test-Paint formulation IV (resin A 50%-2- ethylhexyl acrylate 50%) Substrate: Adhesion, percent Polypropylene 0 Propyleneethylene copolymer 0 Y 'High density polypropylene 0l Control test #5 A fth test is prepared using the same procedure Vexcept that in the paint binder solution the resin component is 1 increased to 75 parts by weight and that of the monovinyl monomer reduced to 25 parts by weight. The adhesion testis carried out upon the cured coatings as in the preceding tests and the results are set yforth below.`

TABLE V Adhesion test- Paint formulation V (resin A methyl methacrylate 25%) Substrate: Adhesion, percent Polypropylene 0 Propylene-ethylene copolymer 0 High density polypropylene 0 Control test #6 TABLE VI Adhesion test- Paint formulation VI (resin A 15 methyl methacrylate Substrate: Adhesion, percent" Polypropylene 0 APropylene-ethylene copolymer 0 l Polyethylene 0- The adhesion failures of vinyl resin-monovinylmonomer paints being thus demonstrated at various resin con- 25 parts by weight of resin A, 45 parts by weight of methv TABLE VII Adhesion test-Paint formulation VII (resin A 25%- methyl methacrylate 4.5%-ethane diol dimethacrylate 30%) Substrate: Adhesion, percent Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene 100 EXAMPLE 2 In order to test for required quantities of the diacrylates and triacrylates used herein and to test the suitability of various diacrylates land triacrylates of the types hereinbefore named, additional tests are carried out. p

An eighth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 25 parts by weight of resin A, 70 parts by weight of methyl methacrylate and 5 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE VIII Adhesion test-Paint formulation VII (resin A 25%- methly methacrylate 70%-ethane diol dimethacrylate 5%) Substrate: Adhesion, percent Polypropylene 10 Propylene-ethylene copolymer 5 High density polyethylene A ninth test is carried out using the same procedure used in the precedinf tests except that the paint binder solution contains 25 parts by weight of resin A, 70 parts by weight of methyl methacrylate and parts by weight of 1,4-butanediol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE IX Adhesion test- Paint formulation IX (resin A 25%- methyl methacrylate 70%-1,4butane diol dimethacrylate 5 Substrate: Adhesion, percent Polypropylene 15 Propylene-ethylene copolymer 15 High density polyethylene 5 A tenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 15 parts by weight of resin A, 80 parts by weight of methyl methacrylate, and 5 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below. y

TABLE X Adhesion test- Paint formulation X (resin A 15%4 methyl methacrylate 80%-ethane diol dimethacrylate 5%) Substrate: Adhesion, percent Polypropylene l l5 Propylene-ethylene copolymer High density polyethylene 5 p TABLE XI Adhesion test-Paint formulation XI (resin A 25%- methyl methacrylate 65 %ethane diol dimethacrylate 10%) Substrate:` Adhesion, percent Polypropylene 30 Propylene-ethylene copolymer 30 High density polyethylene 15 A twelfth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 25 parts by weight of resin A, 60 parts by weight of methyl methacrylate, and 15 parts by weight of 1,4-butanediol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XII Adhesion test- Paint formulation XII (resin A 25%- methyl methacrylate 60%1,4butane diol dimethacrylate 15%) Substrate: Adhesion, percent Polypropylene 6() Propylene-ethylene copolymer 50 High density polyethylene 40 A thirteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 50 parts by weight of resin A, 35 parts by weight of methyl methacrylate and l5 parts by weight of 1,4ebutane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XIII Adhesion test.-Paint formulation XIII (resin A 50%- methyl methacrylate 35 %1,4butane diol dimethacrylate 15%) Substrate: Adhesion, percent Polypropylene 50 Propylene-ethylene copolymer 45 High density polyethylene 30 A fourteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains SO'partsv by weight of resin A, 35 parts by Weight of butyl acrylate, and 15 parts by Weight of 1,4-butane diol dimethacrylate. The adhesion test is carried ont upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XIV Adhesion test- Paint formulation XIV (resin A 50%- `butyl acrylate 35 %1,4butane diol dimethacrylate 15 Substrate: Adhesion, percent Polypropylene I 60 Propylene-ethylene copolymer 45 High density polyethylene 30 A fifteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 50 parts by weight of resin A, 35 parts by weight of 2-ethylhexy1 acrylate, and 15 parts by weight of 1,4-butane diol dimethacrylateThe adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XV Adhesion test.-Paint formulation XV (resin A 50%2- ethylhexyl acrylate 35%1,4-butane diol dimethacrylate Substrate: Adhesion, percent Polypropylene 65 Propylene-ethylene copolymer` 55 High density polyethylene 35 A sixteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 15 parts by weight of resin A, 35 parts by weight of methyl methacrylate, 35 parts by weight of cedure used in the preceding tests except that the paint binder solution contains 50 parts by weight 0f resin A, 35 parts by weight of methyl methacrylate, and 15 parts by weight of 1,6-hexanediol dimethacrylate. The adhesion test is carried out upon the cured coatings `as in the preceding tests and the results are set forth below.

TABLE XVII Adhesion test-Paint formulation XVII (resin A 50%- methyl methacrylate 35 %l,6hexane diol dimethacrylate 15 Substrate: Adhesion, percent Polypropylene 65 Propylene-ethylene copolymer 65 High density polyethylene 60 An eighteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 25 parts by Weight of resin A, 55 parts by weight of methyl methacrylate, and 20 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forthbelow.

`TABLE XVIII Adhesion test.-Paint formulation XVIII (resin A 25%- methyl methacry1ate^'"55%ethane` diol dimethacrylate 20% Substrate: Adhesion, percent Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene 85 A nineteenth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 50 parts by weight of resin A, 30 parts by weight of methyl methacrylate, and 20 parts by Iweight of 1,4-butane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XIX Adhesion test.-Paint formulation XIX (resin A 50%- methyl methacrylate `30%-L4-butane diol dimethacrylate 20%) Substrate: Adhesion, percent Polypropylene 90 Propylene-ethylene copolymer 90 High density polyethylene 80 A twentieth test is carried out using the same procedure used in the preceding tests except that the .paint binder solution contains 25 parts by weight of resin A, 55 parts by Weight of lmethyl methacrylate, and 20 parts by weight of 1,6-hexane diol diacrylatc. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TAB LE XX Adhesion test.-Paint formulation XX A(resin A 25%.- methyl methacrylate 55%-1,6 hexane diol dimethacrylate 20%) Substrate: Adhesion, percent Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene A twenty-first test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 50 parts lby weight of resin A, 30 parts by weight of methyl methacrylate, and 20 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XXI Adhesion test.-Paint formulation XXI (resin A 50%- methyl methacrylate 30%-ethane diol dimethacrylate 20%) Substrate: Adhesion, percent Polypropylene 80 Propylene-ethylene copolymer 75 High density polyethylene 60 A twenty-second test is carried out using the same procedure used in the preceding tests except that the paint binder soluion contains 50 parts by Weight of resin A, -30 parts by weight of methyl methacrylate, and 20 parts by Weight of tetraethylene glycol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below. i

TABLE XXII Adhesion test-Paint formulation XXII (resin A 50%- methyl methacrylate 30%-tetraethylene glycol dimethacrylate 20%) Substrate: Adhesion, percent Polypropylene Propylene-ethylene copolymer 90 High density polyethylene 80 A twenty-third test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 75 parts by weight resin A, 5 parts by weight of methyl methacrylate, and 20 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XXIII Adhesion test- Paint formulation XXIII (resin A 75 methyl methacrylate 5%-ethane diol dimethacrylate 20% Substrate: Adhesion, percent Polypropylene 80 Propylene-ethylene copolymer 70 High density polyethylene 65 A twenty-fourth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 25 parts by weight of resin A, 45 parts by weight of methyl methacrylate, and 30 parts by weight-of 1,6-hexane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth as follows.

9 TABLE XXIV Adhesion test.-Paint formulation (resin A 25 methyl methacrylate 45,%11,6-he xane dioldimethacrylate 30%) Substrate: Adhesion, percent Polypropylene ..V 100 Propylene-ethylene copolymer 100 High density polyethylene `100 A twenty-fifth test is carried out using the v'same procedure used in the preceding tests except that thepaint binder solution contains 25 parts by weight of resin A, 45 parts by weight of methyl methacrylate, and 30 parts by weight of diethylene glycol dimethacrylate. TheV adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TAB LE XXV Adhesion test-Paint formulation XXV (resin A 25 methyl methacrylate 45%- diethylene Iglycol dimethacrylate 30%) Substrate: Adhesion, percent Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene A100 K A TABLE XXVI Adhesion Test- Paint formulation XXVI (resin A 25 methyl methacrylate 45%- tetrapropylene glycol ydimethacrylate 30%) "Adhesion, percent Substrate:

Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene r ..v 100 A twenty-seventh test is carried outusing the saine procedure used in the preceding tests except that the paint binder solution contains 25 partsA by weightof resin A, 45 parts by weight of methyl methacrylate, and *30 parts by weight of trimethylolpropane triacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth'vbelow.

TABLE XXVII Adhesion test- Paint formulation (resin iA- 25 methyl methacrylate 45%- tr'imethylolpropane triacrylate 30%) Substrate: 1 Adhesion, percent Polypropylene 100 Propylene-ethylene copolymer 100 High density polyethylene 100 A twenty-eighth test is carried out using theV same procedure used in the preceding testsexcept that thepaint binder solution contains 25 parts by weight of resinv A, 45 parts by weight of methyl methacrylate, andv ',30'parts by weight of 1,5,l2-dodecane triol trimethacrylateThe adhesion test is carried out upon the cured 'coatings as in the preceding tests and the results are set forth below,

TABLE XXVIII A twenty-ninth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 25 parts by Weight of resin A, 30 parts by-weight of methyl methacrylate, and 45 parts by weight of ethane diol dimethacrylate. The adhesion test is carried out upon the cured coatings as in the preceding tests and the results are set forth below.

TABLE XXIX Adhesion test.-Paint formulation XXIX (resin A 25%- methyl methacrylate 30%-ethane diol dimethacrylate 45% Substrate: Adhesion, percent lPolypropylene Propylene-ethylene copolymer 100 High density polyethylene 100 EXAMPLE 3 A thirtieth test is carried out using the same procedure used in the preceding tests except that the paint binder solution contains 60 parts by weight of resin A and 40 parts by weight of ethane diol dimethacrylate. Adhesion is obtained commensurate with-the tests in Example 2 wherein the paint binder solution contains at least 20 weight percent of the diacrylate.

EXAMPLE 4 The procedure of Example 1 is repeated with the single difference that the electrons of the beam have an average energy of electron 350,000 volts.

EXAMPLE 5 The procedure The procedure of Example l is repeated with the single difference that the atmosphere of irradiation is helium.

EXAMPLE 6 The procedures of Examples 1 and 2 are repeated with the single difference that resin A is replaced with resin B. Resin B is prepared from the following ingredients in the following manner.

Step I: Parts by weight Ethyl acrylate 38.8 Methyl methacrylate 23.2 Allyl glycidyl ether 37.0 Benzoyl peroxide 1.0 Xylene Solvent To a reaction vessel provided with a condenser, thermometer, agitator, and dropping funnel there is charged an amount of xylene equal in weight to the reactants to be added in the first reaction step. The xylene is heated to'about 100 120 C. The four reactants are thoroughly mixed and added slowly with a dropping funnel to the heated Xylene over a period of four hours. The reaction is held at thisrtemperature for 1-2 hours after addition is complete and then allowed to cool to room temperature. The copolymer formed by this procedure is further reacted inthe following manner. l

Step II: Parts by weight Copolymer from step I 69.4 Allyl alcohol 30.4 Potassium hydroxide 0.2

A solution of the allyl alcohol and potassium hydroxide is added to the'copolymer at room temperature, The mix# ture is then heated to a temperature of 100 l20 C. This temperature is maintained Vfor about 7 hours and allowed to cool'. The'A binder polymer reaction mixture is heated to about 60 C. and the xylene and excess reactant are removed by vacuum distillationv 1 1 EXAMPLE 7 The procedures of Examples 1 and 2 are repeated with the single difference that resin A is replaced with resin C. Resin C is prepared from the following ingredients in the following manner.

Step I: Parts by weight Ethyl acrylate 39 Methyl methacrylate 24 Allyl alcohol 36 Benzoyl peroxide 1 Xylene Solvent To a reaction vessel provided with a condenser, thermometer, agitator, and dropping funnel there `is charged an amount of xylene equal in weight to the reactants to be added in the first reaction step. The xylene is heated to about 100-120 C. The four reacting materials are thoroughly mixed and added slowly with a dropping funnel to the heated xylene over a period of four hours. The reaction is held at this temperature 1-2 hours after addition is complete and then allowed to cool to room temperature.

The copolymer formed by this procedure is further reacted in the following manner.

Step Il: Parts by weight Copolymer from step I 69 Allyl glycidyl ether 30.8 Potassium hydroxide A solution of the allyl glycidyl ether and potassium hydroxide is added to the copolymer at room temperature. The mixture is then heated to a temperature of 100-l20 C. This temperature is maintained for about seven hours and allowed to cool. The binder polymer reaction mixture is heated to about `60 C. and the xylene and excess'reactant are removed by vacuum distillation.

'EXAMPLE 8 The procedures of Examples 1 and 2 are repeated with the single difference that resin A is replaced with resin D. IResin D is prepared from the following ingredients in the following manner.

Step I: Parts by weight Methyl methacrylate 400 Ethyl acrylate 400 Hydroxy ethyl methacrylate 195 Toluene 1000 Benzoyl peroxide 30 The benzoyl peroxide is dissolved in a solution of the methyl methacrylate, ethyl acrylate, and hydroxyethyl methacrylate and one-half of the toluene. This solution is added incrementally to the remainder of the toluene at reflux over a seven-hour period with a final pot temperature of about 138-140 C. Rellux is maintained for another three hours and the solution cooled.

Step II: Parts by weight Solution from step I 500 Acrylyl chloride 33.8 Toluene 30 like manner at right angles tothe first group and crossing same. Adhesive cellophane tape is then applied over the scored' surface vand removed. Adhesion is measured from the number of paint squares remaining in the taped area relative to paint squares removed. Tape having the same adhesive quality is used in allutests. It is applied to the coated surface and'removed therefrom in the same manner for all tests.

The abbreviation ra as employed herein means that dose of radiation which results in the absorption of 100 ergs of energy per gram of absorber, e.g. coating lilm. The abbreviation mrad as employed herein means 1 million rad. The electron emitting means may be a linear electron accelerator capable of producing a direct current potential in the range of about 100,000 to about 500,000 volts. In' such a device electrons are ordinarily emitted from a hot filament and accelerated through a uniform voltagev gradient. The electron beam, which may be about 1A; inch in diameter at this point, may then be scanned to make a fan-shaped beam and then passed through a metal window, e.g. a magnesium thorium alloy, aluminum, an alloy of aluminum and a minor amount of copper, etc., of about 0.003V inch thickness. The irradiation is preferably carried .out in a substantially oxygen-free atmosphere, e.g. nitrogen, helium, etc.

Y It will be understood by those skilled in the art that modifications can be made within the foregoing examples without departing from the spirit and scope of the invention as set forth in the following claims.

' What is claimed is:

1. In a method for coating a solid substrate of polyolefin with a vinyl copolymer crosslinked with vinyl monomers, the improvement which comprises applying to the polyolen substrate a coating of a film-forming vsolution which on a pigment and particulate ller-free basis, consists essentially of (A) about 15 to about 45 weight percent acrylate selected from the group consisting of diacrylates and dimethacrylates of a CZ-Cm alkane diol, diacrylates and dimethacrylates of a C4-C12 polylether diol, and triacrylatesl of a C6-C12 triol, and (B) 55 to weight percent of a vinyl resin-comprising com- 'ponent consisting of 0 to about 85 weight percent monovinyl monomers and about 15 to about 100 weight percent of an alpha-beta olenically unsaturated copolymer of acrylic monomers having average molecular weight between 1,000 arid 25,000 and 0.5 to 5 units of alpha-beta oleiinic unsaturation per 1,000 units molecular weight and crosslinking said coating on said polyoleiin substrate by exposing said coatingto a beam of polymerization effecting electrons having average energy in the range of about 100,000 to about 500,000 electron volts in a substantially oxygen-free atmosphere.

2. A method in accordance with claim 1 wherein said acrylate of (A) comprises between 20 and 35 percent of said film-forming solution.

l 3. A method in accordance with claim 1 wherein said copolymer of acrylic monomers has average molecular weight in the range of about 5,000 to about 15,000 and about 0.7 to about 3 units of alpha-beta olefinic unsaturation per 1,000 units molecular weight.

` y4. A method in accordance with claim 1 wherein said copolymeruof acrylic monomers has average molecular weight in the range of about 5,000 to about 15,000 and about 0 .7 to about 3 units of alpha-beta olenc unsatura- 'tion per 1,000 units molecular weight and is a copolymer of a glycidyl acrylate'selected from glycidyl acrylate and glycidyl methacrylate, and a monoester acrylate selected from esters of acrylic or methacrylic acid and a C1 to Ca monohydric alcohol, said copolymer having been reacted with acrylic or methacrylic acid to introduce said units of alpha-beta olefinic ulnsaturation.

5. A method in accordance with claim 1 wherein said substantially oxygen-freeatmosphere is essentially a nitrogen atmosphere.

1 14 6. A method in accordance with claim 1 wherein said 3,528,844 9/ 1970 Burlant et al 117-93.31 electrons have average energy in the range of about 3,560,245 2/ 1971 Aronoff et al -117-9331 150,000 to about 450,000 electron volts.

WILLIAM D. MARTIN, Pn'mary Examiner References Cited 5 UNITED STATES PATENTS I. H. NEWSOME, Asslstant Exammer 3,552,986 1/ 1971 Bassemir et al. 117-161 UC U S CL XR' 3,265,764 8/1966 Deichert et al. 1l7-138.8 E 3,318,975 5/1967 Deichert et al. 117-138.8 E 10 117-138.8 E, 161 UC; 204-159.16; 260-875 

